The Collaborative International Dictionary of English v.0.48:

Skylark \Sky"lark`\, n. (Zool.)
   A lark that mounts and sings as it files, especially the
   common species (Alauda arvensis) found in Europe and in
   some parts of Asia, and celebrated for its melodious song; --
   called also sky laverock. See under Lark.
   [1913 Webster]

   Note: The Australian skylark (Cincloramphus cantillans) is
         a pipit which has the habit of ascending
         perpendicularly like a skylark, but it lacks the song
         of a true lark. The Missouri skylark is a pipit
         (Anthus Spraguei) of the Western United States,
         resembling the skylark in habit and song.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pipit \Pip"it\, n. [So named from its call note.] (Zool.)
   Any one of numerous species of small singing birds belonging
   to Anthus and allied genera, of the family
   Motacillid[ae]. They strongly resemble the true larks in
   habits, colors, and the great length of the hind claw. They
   are, therefore, often called titlarks, and pipit larks.
   [1913 Webster]

   Note: The meadow pipit (Anthus pratensis); the tree
         pipit, or tree lark (Anthus trivialis); and the
         rock pipit, or sea lark (Anthus obscurus) are
         well-known European species. The common American pipit,
         or brown lark, is Anthus Pensilvanicus. The Western
         species (Anthus Spraguei) is called the American
         skylark, on account of its musical powers.
         [1913 Webster]